The semiconductor industry has benefited from in-situ dry cleaning procedures made possible by exciting nitrogen trifluoride in a plasma and flowing the plasma effluents to clean interior surfaces of a substrate processing chamber. In-situ cleaning procedures avoid requiring chamber disassembly while still removing undesired substances such as silicon nitride, polycrystalline silicon, silicides and silicon dioxide. Removing these undesired substances before additional substrate processing may reduce defects and control electro-mechanical properties of processed layers.
Nitrogen trifluoride (NF3), has been widely selected as a precursor to generate fluorine/fluorine radicals in-situ over the use of fluorine (F2) as a direct result of its ease of handling and cost. The relatively high cost of nitrogen trifluoride combined with speculation that the agent has a high global warming potential (GWP), are causing manufacturers to look for ways to use less NF3 per preventative maintenance procedure. Thus there is a need for new chamber cleaning agents which more effectively remove contaminants from the interior surfaces of substrate processing chambers and produce more eco-friendly exhaust gases.
Carbonyl Fluoride (COF2) is an extremely reactive and toxic gas. Carbonyl Fluoride (COF2) reacts with water (ubiquitous in the environment) to produce hydrogen fluoride, itself a toxic and corrosive gas, and carbon dioxide, and COF2is difficult to purify. Additionally, there are shelf life concerns in cylinder packaging for COF2, thus yielding an unstable output that contains a variety of the above mentioned hazardous compounds that may not be fortuitous to a process. Fortunately, the precautions for safe storage, handling and use are well documented; however, the cost for implementing the measures is high versus less hazardous materials. The high cost of manufacture and distribution of carbonyl fluoride (COF2) are also impacted by its hazardous properties. Combined, these two facts result in an integrated cost of ownership for implementing and using carbonyl fluoride (COF2) that is commercially questionable. Especially cost prohibitive is retrofitting existing locations where carbonyl fluoride (COF2) would provide a benefit. In the semiconductor, flat-panel and solar industries, nitrogen trifluoride (NF3), oxides of carbon (COx where x=1 or 2) and numerous perfluorocarbon compounds (CyFz) are already is use. Generating Carbonyl Fluoride (COF2) in-situ from safer, familiar materials allows the technical benefits described herein to be attainable whilst reducing the infrastructure costs and time required to implement and avoids the need of supplying COF2 in a cylinder package.